/*
 * Copyright 1999-2018 Alibaba Group Holding Ltd.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package com.alibaba.nacos.client.identify;
/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 * 
 *      http://www.apache.org/licenses/LICENSE-2.0
 * 
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

import java.io.UnsupportedEncodingException;

/**
* Provides Base64 encoding and decoding as defined by <a href="http://www.ietf.org/rfc/rfc2045.txt">RFC 2045</a>.
* 
* <p>
* This class implements section <cite>6.8. Base64 Content-Transfer-Encoding</cite> from RFC 2045 <cite>Multipurpose
* Internet Mail Extensions (MIME) Part One: Format of Internet Message Bodies</cite> by Freed and Borenstein.
* </p>
* <p>
* The class can be parameterized in the following manner with various constructors:
* <ul>
* <li>URL-safe mode: Default off.</li>
* <li>Line length: Default 76. Line length that aren't multiples of 4 will still essentially end up being multiples of
* 4 in the encoded data.
* <li>Line separator: Default is CRLF ("\r\n")</li>
* </ul>
* </p>
* <p>
* Since this class operates directly on byte streams, and not character streams, it is hard-coded to only encode/decode
* character encodings which are compatible with the lower 127 ASCII chart (ISO-8859-1, Windows-1252, UTF-8, etc).
* </p>
* <p>
* This class is not thread-safe. Each thread should use its own instance.
* </p>
* 
* @see <a href="http://www.ietf.org/rfc/rfc2045.txt">RFC 2045</a>
* @author Apache Software Foundation
* @since 1.0
* @version $Revision: 1080712 $
*/
public class Base64 {

   /**
    * BASE32 characters are 6 bits in length. 
    * They are formed by taking a block of 3 octets to form a 24-bit string, 
    * which is converted into 4 BASE64 characters.
    */
   private static final int BITS_PER_ENCODED_BYTE = 6;
   private static final int BYTES_PER_UNENCODED_BLOCK = 3;
   private static final int BYTES_PER_ENCODED_BLOCK = 4;

   /**
    * Chunk separator per RFC 2045 section 2.1.
    *
    * <p>
    * N.B. The next major release may break compatibility and make this field private.
    * </p>
    * 
    * @see <a href="http://www.ietf.org/rfc/rfc2045.txt">RFC 2045 section 2.1</a>
    */
   static final byte[] CHUNK_SEPARATOR = {'\r', '\n'};

   /**
    * This array is a lookup table that translates 6-bit positive integer index values into their "Base64 Alphabet"
    * equivalents as specified in Table 1 of RFC 2045.
    * 
    * Thanks to "commons" project in ws.apache.org for this code.
    * http://svn.apache.org/repos/asf/webservices/commons/trunk/modules/util/
    */
   private static final byte[] STANDARD_ENCODE_TABLE = {
           'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I', 'J', 'K', 'L', 'M',
           'N', 'O', 'P', 'Q', 'R', 'S', 'T', 'U', 'V', 'W', 'X', 'Y', 'Z',
           'a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i', 'j', 'k', 'l', 'm',
           'n', 'o', 'p', 'q', 'r', 's', 't', 'u', 'v', 'w', 'x', 'y', 'z',
           '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', '+', '/'
   };

   /**
    * This is a copy of the STANDARD_ENCODE_TABLE above, but with + and /
    * changed to - and _ to make the encoded Base64 results more URL-SAFE.
    * This table is only used when the Base64's mode is set to URL-SAFE.
    */    
   private static final byte[] URL_SAFE_ENCODE_TABLE = {
           'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I', 'J', 'K', 'L', 'M',
           'N', 'O', 'P', 'Q', 'R', 'S', 'T', 'U', 'V', 'W', 'X', 'Y', 'Z',
           'a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i', 'j', 'k', 'l', 'm',
           'n', 'o', 'p', 'q', 'r', 's', 't', 'u', 'v', 'w', 'x', 'y', 'z',
           '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', '-', '_'
   };

   /**
    * This array is a lookup table that translates Unicode characters drawn from the "Base64 Alphabet" (as specified in
    * Table 1 of RFC 2045) into their 6-bit positive integer equivalents. Characters that are not in the Base64
    * alphabet but fall within the bounds of the array are translated to -1.
    * 
    * Note: '+' and '-' both decode to 62. '/' and '_' both decode to 63. This means decoder seamlessly handles both
    * URL_SAFE and STANDARD base64. (The encoder, on the other hand, needs to know ahead of time what to emit).
    * 
    * Thanks to "commons" project in ws.apache.org for this code.
    * http://svn.apache.org/repos/asf/webservices/commons/trunk/modules/util/
    */
   private static final byte[] DECODE_TABLE = {
           -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
           -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
           -1, -1, -1, -1, -1, -1, -1, -1, -1, 62, -1, 62, -1, 63, 52, 53, 54,
           55, 56, 57, 58, 59, 60, 61, -1, -1, -1, -1, -1, -1, -1, 0, 1, 2, 3, 4,
           5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23,
           24, 25, -1, -1, -1, -1, 63, -1, 26, 27, 28, 29, 30, 31, 32, 33, 34,
           35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51
   };

   /**
    * Base64 uses 6-bit fields. 
    */
   /** Mask used to extract 6 bits, used when encoding */
   private static final int MASK_6BITS = 0x3f;

   // The static final fields above are used for the original static byte[] methods on Base64.
   // The private member fields below are used with the new streaming approach, which requires
   // some state be preserved between calls of encode() and decode().

   /**
    * Encode table to use: either STANDARD or URL_SAFE. Note: the DECODE_TABLE above remains static because it is able
    * to decode both STANDARD and URL_SAFE streams, but the encodeTable must be a member variable so we can switch
    * between the two modes.
    */
   private final byte[] encodeTable;

	/**
	 * Only one decode table currently; keep for consistency with Base32 code
	 */
   private final byte[] decodeTable = DECODE_TABLE;

   /**
    * Line separator for encoding. Not used when decoding. Only used if lineLength > 0.
    */
   private final byte[] lineSeparator;

   /**
    * Convenience variable to help us determine when our buffer is going to run out of room and needs resizing.
    * <code>decodeSize = 3 + lineSeparator.length;</code>
    */
   private final int decodeSize;

   /**
    * Convenience variable to help us determine when our buffer is going to run out of room and needs resizing.
    * <code>encodeSize = 4 + lineSeparator.length;</code>
    */
   private final int encodeSize;

   /**
    * Place holder for the bytes we're dealing with for our based logic. 
    * Bitwise operations store and extract the encoding or decoding from this variable.
    */
   private int bitWorkArea;

   /**
    * Creates a Base64 codec used for decoding (all modes) and encoding in URL-unsafe mode.
    * <p>
    * When encoding the line length is 0 (no chunking), and the encoding table is STANDARD_ENCODE_TABLE.
    * </p>
    * 
    * <p>
    * When decoding all variants are supported.
    * </p>
    */
   public Base64() {
       this(0, CHUNK_SEPARATOR, false);
   }

   /**
    * Creates a Base64 codec used for decoding (all modes) and encoding in URL-unsafe mode.
    * <p>
    * When encoding the line length and line separator are given in the constructor, and the encoding table is
    * STANDARD_ENCODE_TABLE.
    * </p>
    * <p>
    * Line lengths that aren't multiples of 4 will still essentially end up being multiples of 4 in the encoded data.
    * </p>
    * <p>
    * When decoding all variants are supported.
    * </p>
    * 
    * @param lineLength
    *            Each line of encoded data will be at most of the given length (rounded down to nearest multiple of 4).
    *            If lineLength <= 0, then the output will not be divided into lines (chunks). Ignored when decoding.
    * @param lineSeparator
    *            Each line of encoded data will end with this sequence of bytes.
    * @param urlSafe
    *            Instead of emitting '+' and '/' we emit '-' and '_' respectively. urlSafe is only applied to encode
    *            operations. Decoding seamlessly handles both modes.
    * @throws IllegalArgumentException
    *             The provided lineSeparator included some base64 characters. That's not going to work!
    * @since 1.4
    */
   public Base64(int lineLength, byte[] lineSeparator, boolean urlSafe) {
       chunkSeparatorLength = lineSeparator == null ? 0 : lineSeparator.length;
       unencodedBlockSize = BYTES_PER_UNENCODED_BLOCK;
       encodedBlockSize = BYTES_PER_ENCODED_BLOCK;
       this.lineLength = (lineLength > 0  && chunkSeparatorLength > 0) ? (lineLength / encodedBlockSize) * encodedBlockSize : 0;
       // TODO could be simplified if there is no requirement to reject invalid line sep when length <=0
       // @see test case Base64Test.testConstructors() 
       if (lineSeparator != null) {
           if (containsAlphabetOrPad(lineSeparator)) {
               String sep = null;
               try {
                   sep = new String(lineSeparator, "UTF-8");
               } catch (UnsupportedEncodingException e) {
               }
               throw new IllegalArgumentException("lineSeparator must not contain base64 characters: [" + sep + "]");
           }            
           if (lineLength > 0){
               this.encodeSize = BYTES_PER_ENCODED_BLOCK + lineSeparator.length;
               this.lineSeparator = new byte[lineSeparator.length];
               System.arraycopy(lineSeparator, 0, this.lineSeparator, 0, lineSeparator.length);
           } else {
               this.encodeSize = BYTES_PER_ENCODED_BLOCK;
               this.lineSeparator = null;
           }
       } else {
           this.encodeSize = BYTES_PER_ENCODED_BLOCK;
           this.lineSeparator = null;
       }
       this.decodeSize = this.encodeSize - 1;
       this.encodeTable = urlSafe ? URL_SAFE_ENCODE_TABLE : STANDARD_ENCODE_TABLE;
   }

   /**
    * <p>
    * Encodes all of the provided data, starting at inPos, for inAvail bytes. Must be called at least twice: once with
    * the data to encode, and once with inAvail set to "-1" to alert encoder that EOF has been reached, so flush last
    * remaining bytes (if not multiple of 3).
    * </p>
    * <p>
    * Thanks to "commons" project in ws.apache.org for the bitwise operations, and general approach.
    * http://svn.apache.org/repos/asf/webservices/commons/trunk/modules/util/
    * </p>
    * 
    * @param in
    *            byte[] array of binary data to base64 encode.
    * @param inPos
    *            Position to start reading data from.
    * @param inAvail
    *            Amount of bytes available from input for encoding.
    */
   void encode(byte[] in, int inPos, int inAvail) {
       if (eof) {
           return;
       }
       if (inAvail < 0) {
           eof = true;
           if (0 == modulus && lineLength == 0) {
               return;
           }
           ensureBufferSize(encodeSize);
           int savedPos = pos;
           switch (modulus) {
               case 1 :
                   buffer[pos++] = encodeTable[(bitWorkArea >> 2) & MASK_6BITS];
                   buffer[pos++] = encodeTable[(bitWorkArea << 4) & MASK_6BITS];
				
                   if (encodeTable == STANDARD_ENCODE_TABLE) {
                       buffer[pos++] = PAD;
                       buffer[pos++] = PAD;
                   }
                   break;

               case 2 :
                   buffer[pos++] = encodeTable[(bitWorkArea >> 10) & MASK_6BITS];
                   buffer[pos++] = encodeTable[(bitWorkArea >> 4) & MASK_6BITS];
                   buffer[pos++] = encodeTable[(bitWorkArea << 2) & MASK_6BITS];
                   
                   if (encodeTable == STANDARD_ENCODE_TABLE) {
                       buffer[pos++] = PAD;
                   }
                   break;
			   default:
				   break;
           }
           currentLinePos += pos - savedPos; 
			/**
			 * if currentPos == 0 we are at the start of a line, so don't add CRLF
			 */
           if (lineLength > 0 && currentLinePos > 0) { 
               System.arraycopy(lineSeparator, 0, buffer, pos, lineSeparator.length);
               pos += lineSeparator.length;
           }
       } else {
           for (int i = 0; i < inAvail; i++) {
               ensureBufferSize(encodeSize);
               modulus = (modulus+1) % BYTES_PER_UNENCODED_BLOCK;
               int b = in[inPos++];
               if (b < 0) {
                   b += 256;
               }
               bitWorkArea = (bitWorkArea << 8) + b;
               if (0 == modulus) {
                   buffer[pos++] = encodeTable[(bitWorkArea >> 18) & MASK_6BITS];
                   buffer[pos++] = encodeTable[(bitWorkArea >> 12) & MASK_6BITS];
                   buffer[pos++] = encodeTable[(bitWorkArea >> 6) & MASK_6BITS];
                   buffer[pos++] = encodeTable[bitWorkArea & MASK_6BITS];
                   currentLinePos += BYTES_PER_ENCODED_BLOCK;
                   if (lineLength > 0 && lineLength <= currentLinePos) {
                       System.arraycopy(lineSeparator, 0, buffer, pos, lineSeparator.length);
                       pos += lineSeparator.length;
                       currentLinePos = 0;
                   }
               }
           }
       }
   }

   /**
    * <p>
    * Decodes all of the provided data, starting at inPos, for inAvail bytes. Should be called at least twice: once
    * with the data to decode, and once with inAvail set to "-1" to alert decoder that EOF has been reached. The "-1"
    * call is not necessary when decoding, but it doesn't hurt, either.
    * </p>
    * <p>
    * Ignores all non-base64 characters. This is how chunked (e.g. 76 character) data is handled, since CR and LF are
    * silently ignored, but has implications for other bytes, too. This method subscribes to the garbage-in,
    * garbage-out philosophy: it will not check the provided data for validity.
    * </p>
    * <p>
    * Thanks to "commons" project in ws.apache.org for the bitwise operations, and general approach.
    * http://svn.apache.org/repos/asf/webservices/commons/trunk/modules/util/
    * </p>
    * 
    * @param in
    *            byte[] array of ascii data to base64 decode.
    * @param inPos
    *            Position to start reading data from.
    * @param inAvail
    *            Amount of bytes available from input for encoding.
    */
   void decode(byte[] in, int inPos, int inAvail) {
       if (eof) {
           return;
       }
       if (inAvail < 0) {
           eof = true;
       }
       for (int i = 0; i < inAvail; i++) {
           ensureBufferSize(decodeSize);
           byte b = in[inPos++];
           if (b == PAD) {
               // We're done.
               eof = true;
               break;
           } else {
               if (b >= 0 && b < DECODE_TABLE.length) {
                   int result = DECODE_TABLE[b];
                   if (result >= 0) {
                       modulus = (modulus+1) % BYTES_PER_ENCODED_BLOCK;
                       bitWorkArea = (bitWorkArea << BITS_PER_ENCODED_BYTE) + result;
                       if (modulus == 0) {
                           buffer[pos++] = (byte) ((bitWorkArea >> 16) & MASK_8BITS);
                           buffer[pos++] = (byte) ((bitWorkArea >> 8) & MASK_8BITS);
                           buffer[pos++] = (byte) (bitWorkArea & MASK_8BITS);
                       }
                   }
               }
           }
       }

       // Two forms of EOF as far as base64 decoder is concerned: actual
       // EOF (-1) and first time '=' character is encountered in stream.
       // This approach makes the '=' padding characters completely optional.
       if (eof && modulus != 0) {
           ensureBufferSize(decodeSize);
           
           // We have some spare bits remaining
           // Output all whole multiples of 8 bits and ignore the rest
           switch (modulus) {
          //   case 1: // 6 bits - ignore entirely
          //       break;
               case 2 : 
                   bitWorkArea = bitWorkArea >> 4;
                   buffer[pos++] = (byte) ((bitWorkArea) & MASK_8BITS);
                   break;
               case 3 :
                   bitWorkArea = bitWorkArea >> 2; 
                   buffer[pos++] = (byte) ((bitWorkArea >> 8) & MASK_8BITS);
                   buffer[pos++] = (byte) ((bitWorkArea) & MASK_8BITS);
				   break;
			   default:
				   break;
           }
       }
   }
   
   /**
    * Encodes binary data using the base64 algorithm but does not chunk the output.
    * 
    * @param binaryData
    *            binary data to encode
    * @return byte[] containing Base64 characters in their UTF-8 representation.
    */
   public static byte[] encodeBase64(byte[] binaryData) {
       return encodeBase64(binaryData, false, false, Integer.MAX_VALUE);
   }

   /**
    * Encodes binary data using the base64 algorithm, optionally chunking the output into 76 character blocks.
    * 
    * @param binaryData
    *            Array containing binary data to encode.
    * @param isChunked
    *            if <code>true</code> this encoder will chunk the base64 output into 76 character blocks
    * @param urlSafe
    *            if <code>true</code> this encoder will emit - and _ instead of the usual + and / characters.
    * @param maxResultSize
    *            The maximum result size to accept.
    * @return Base64-encoded data.
    * @throws IllegalArgumentException
    *             Thrown when the input array needs an output array bigger than maxResultSize
    * @since 1.4
    */
   public static byte[] encodeBase64(byte[] binaryData, boolean isChunked, boolean urlSafe, int maxResultSize) {
       if (binaryData == null || binaryData.length == 0) {
           return binaryData;
       }

       // Create this so can use the super-class method
       // Also ensures that the same roundings are performed by the ctor and the code
       Base64 b64 = isChunked ? new Base64(MIME_CHUNK_SIZE, CHUNK_SEPARATOR, urlSafe) : new Base64(0, CHUNK_SEPARATOR, urlSafe);
       long len = b64.getEncodedLength(binaryData);
       if (len > maxResultSize) {
           throw new IllegalArgumentException("Input array too big, the output array would be bigger (" +
               len +
               ") than the specified maximum size of " +
               maxResultSize);
       }
               
       return b64.encode(binaryData);
   }



   /**
    * Decodes Base64 data into octets
    * 
    * @param base64Data
    *            Byte array containing Base64 data
    * @return Array containing decoded data.
    */
   public static byte[] decodeBase64(byte[] base64Data) {
       return new Base64().decode(base64Data);
   }


   /**
    * Returns whether or not the <code>octet</code> is in the Base32 alphabet.
    * 
    * @param octet
    *            The value to test
    * @return <code>true</code> if the value is defined in the the Base32 alphabet <code>false</code> otherwise.
    */
   protected boolean isInAlphabet(byte octet) {
       return octet >= 0 && octet < decodeTable.length && decodeTable[octet] != -1;
   }

   /**
    * Below from base class
    */

   /**
    *  MIME chunk size per RFC 2045 section 6.8.
    *
    * <p>
    * The {@value} character limit does not count the trailing CRLF, but counts all other characters, including any
    * equal signs.
    * </p>
    *
    * @see <a href="http://www.ietf.org/rfc/rfc2045.txt">RFC 2045 section 6.8</a>
    */
   private static final int MIME_CHUNK_SIZE = 76;

   private static final int DEFAULT_BUFFER_RESIZE_FACTOR = 2;

   /**
    * Defines the default buffer size - currently {@value}
    * - must be large enough for at least one encoded block+separator
    */
   private static final int DEFAULT_BUFFER_SIZE = 8192;

   /** Mask used to extract 8 bits, used in decoding bytes */
   private static final int MASK_8BITS = 0xff;

   /**
    * Byte used to pad output.
    */
   private static final byte PAD_DEFAULT = '='; 

   private static final byte PAD = PAD_DEFAULT; 

   /** Number of bytes in each full block of unencoded data, e.g. 4 for Base64 and 5 for Base32 */
   private final int unencodedBlockSize;

   /** Number of bytes in each full block of encoded data, e.g. 3 for Base64 and 8 for Base32 */
   private final int encodedBlockSize;

   /**
    * Chunksize for encoding. Not used when decoding.
    * A value of zero or less implies no chunking of the encoded data.
    * Rounded down to nearest multiple of encodedBlockSize.
    */
   private final int lineLength;

   /**
    * Size of chunk separator. Not used unless {@link #lineLength} > 0.
    */
   private final int chunkSeparatorLength;

   /**
    * Buffer for streaming.
    */
   private byte[] buffer;

   /**
    * Position where next character should be written in the buffer.
    */
   private int pos;

   /**
    * Position where next character should be read from the buffer.
    */
   private int readPos;

   /**
    * Boolean flag to indicate the EOF has been reached. Once EOF has been reached, this object becomes useless,
    * and must be thrown away.
    */
   private boolean eof;

   /**
    * Variable tracks how many characters have been written to the current line. Only used when encoding. We use it to
    * make sure each encoded line never goes beyond lineLength (if lineLength > 0).
    */
   private int currentLinePos;

   /**
    * Writes to the buffer only occur after every 3/5 reads when encoding, and every 4/8 reads when decoding.
    * This variable helps track that.
    */
   private int modulus;

   /**
    * Ensure that the buffer has room for <code>size</code> bytes
    *
    * @param size minimum spare space required
    */
   private void ensureBufferSize(int size){
       if ((buffer == null) || (buffer.length < pos + size)){
           if (buffer == null) {
               buffer = new byte[DEFAULT_BUFFER_SIZE];
               pos = 0;
               readPos = 0;
           } else {
               byte[] b = new byte[buffer.length * DEFAULT_BUFFER_RESIZE_FACTOR];
               System.arraycopy(buffer, 0, b, 0, buffer.length);
               buffer = b;
           }
       }
   }

   /**
    * Extracts buffered data into the provided byte[] array, starting at position bPos,
    * up to a maximum of bAvail bytes. Returns how many bytes were actually extracted.
    *
    * @param b
    *            byte[] array to extract the buffered data into.
    * @param bPos
    *            position in byte[] array to start extraction at.
    * @param bAvail
    *            amount of bytes we're allowed to extract. We may extract fewer (if fewer are available).
    * @return The number of bytes successfully extracted into the provided byte[] array.
    */
   private int readResults(byte[] b, int bPos, int bAvail) {
       if (buffer != null) {
           int len = Math.min(pos - readPos, bAvail);
           System.arraycopy(buffer, readPos, b, bPos, len);
           readPos += len;
           if (readPos >= pos) {
               buffer = null;
           }
           return len;
       }
       return eof ? -1 : 0;
   }

   /**
    * Resets this object to its initial newly constructed state.
    */
   private void reset() {
       buffer = null;
       pos = 0;
       readPos = 0;
       currentLinePos = 0;
       modulus = 0;
       eof = false;
   }

   /**
    * Decodes a byte[] containing characters in the Base-N alphabet.
    *
    * @param pArray
    *            A byte array containing Base-N character data
    * @return a byte array containing binary data
    */
   private byte[] decode(byte[] pArray) {
       reset();
       if (pArray == null || pArray.length == 0) {
           return pArray;
       }
       decode(pArray, 0, pArray.length);
       decode(pArray, 0, -1);
       byte[] result = new byte[pos];
       readResults(result, 0, result.length);
       return result;
   }

   /**
    * Encodes a byte[] containing binary data, into a byte[] containing characters in the alphabet.
    *
    * @param pArray
    *            a byte array containing binary data
    * @return A byte array containing only the basen alphabetic character data
    */
   private byte[] encode(byte[] pArray) {
       reset();
       if (pArray == null || pArray.length == 0) {
           return pArray;
       }
       encode(pArray, 0, pArray.length);
       encode(pArray, 0, -1); 
       byte[] buf = new byte[pos - readPos];
       readResults(buf, 0, buf.length);
       return buf;
   }

   /**
    * Tests a given byte array to see if it contains any characters within the alphabet or PAD.
    *
    * Intended for use in checking line-ending arrays
    *
    * @param arrayOctet
    *            byte array to test
    * @return <code>true</code> if any byte is a valid character in the alphabet or PAD; <code>false</code> otherwise
    */
   private boolean containsAlphabetOrPad(byte[] arrayOctet) {
       if (arrayOctet == null) {
           return false;
       }
       for (int i = 0; i < arrayOctet.length; i++) {
           if (PAD == arrayOctet[i] || isInAlphabet(arrayOctet[i])) {
               return true;
           }
       }
       return false;
   }

   /**
    * Calculates the amount of space needed to encode the supplied array.
    *
    * @param pArray byte[] array which will later be encoded
    *
    * @return amount of space needed to encoded the supplied array.
    * Returns a long since a max-len array will require > Integer.MAX_VALUE
    */
   private long getEncodedLength(byte[] pArray) {
       // Calculate non-chunked size - rounded up to allow for padding
       // cast to long is needed to avoid possibility of overflow
       long len = ((pArray.length + unencodedBlockSize-1)  / unencodedBlockSize) * (long) encodedBlockSize;
       if (lineLength > 0) { 
			/**
			 * Round up to nearest multiple
			 */
           len += ((len + lineLength-1) / lineLength) * chunkSeparatorLength;
       }
       return len;
   }
}
